Ureteral stents and related methods
A medical device for use within a body cavity comprising an elongated body portion and a retention module. The retention module comprises a fixation element and a tether connector. The tether connector and fixation element permit the device to move a predetermined distance longitudinally. The tether connector reduces ureteral reflux, and minimizes irritation and patient discomfort. The fixation element and the tether connector further function as a graspable structure for removal of the stent.
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This invention generally relates to stents and more particularly to ureteral stents.
BACKGROUND INFORMATIONUreteral stents are used to create a pathway for urinary drainage from the kidney to the bladder in patients with ureteral obstruction or injury or to protect the integrity of the ureter in a variety of surgical manipulations. A number of clinical conditions can produce interruption in urine flow including, for example, intrinsic obstruction of the ureter due to tumor growth, stricture or stones, compression of the ureter due to extrinsic tumor growth, stone fragment impactation in the ureter following extracorporeal shock wave lithotripsy (ESWL), and ureteral procedures such as ureteroscopy and endopyelotomy. Stents may be used to treat or avoid obstructions of the ureter (such as ureteral stones or ureteral tumors) that disrupt the flow of urine from the corresponding kidney to the urinary bladder. Serious obstructions of the urinary tract may cause urine to back up into the kidney, threatening renal function. Ureteral stents may also be used after endoscopic inspection of the ureter.
Ureteral stents typically are tubular in shape, terminating in two opposing ends: a kidney distal end and a urinary bladder proximal end. One or both of the ends of the stent may be coiled in a pigtail spiral or J-shape to prevent the upward and/or downward migration of the stent in the lumen of the ureter due, to day-to-day physical activity of the patient, for example. A kidney end coil is designed to retain the stent within the renal pelvis and to prevent stent migration down the ureter. The urinary bladder end coil is positioned in the bladder and is designed to prevent stent migration upward toward the kidney. The bladder end-coil is also used to aid in retrieval and removal of the stent.
A ureteral stent assists in the flow of urine from the kidney to the urinary bladder. The region known as the ureteral vesical junction is a small area of the ureter that is immediately upstream, relative to normal urine flow, to the urinary bladder. The ureteral vesical junction has greater pain sensation relative to other regions of the ureter wall and kidneys and is a major source of patient discomfort when this region of the ureter is in contact with indwelling ureteral stents.
Ureteral stents, particularly the portion positioned in the ureter and proximal to the bladder, may produce adverse effects including hemorrhage, a continual urge to urinate, flank pain accompanying reflux of urine back up the ureter due to retrograde pressure when voiding, and trigone irritation resulting from chronic irritation due to the bladder anchoring features of the stent or resulting from intraoperative trauma inflicted from passage of the device in the ureter. In summary, stents may cause or contribute to significant patient discomfort and serious medical problems.
SUMMARY OF THE INVENTIONIn general, one aspect of the invention described herein relates to a medical device for use within a body tract such as a duct, tube or vessel. In one embodiment of this aspect of the invention, the medical device has an elongated body portion defining a lumen and a proximal portion with a proximal end, a distal portion with a distal end, and a retention module disposed proximal to the proximal end of the elongated body portion. The retention module retains the proximal end of the body portion of the stent in the ureter just distal to the urinary bladder. The retention module further includes a fixation element attached to the elongated body portion by a tether connector. The tether connector reduces ureteral reflux and patient discomfort by permitting the ureteral orifice to contract more completely around the tether connector during voiding (urination) than is possible around the elongated body portion of the stent. The tether connector or the fixation element of the retention module may also be a suitable structure for grasping and removal of the stent from the body.
In another embodiment, the fixation element of the retention module is substantially buoyant. In this embodiment, the buoyant fixation element may float on the urine within the bladder thereby minimizing contact of the fixation element with the tri gone of the bladder. In some embodiments, the fixation element of the retention module is of a size and configuration so as to prohibit the passage of said fixation element from the lumen of the urinary bladder into the lumen of the ureter and to allow the endoscopic introduction of the fixation element into the urinary bladder.
In other embodiments, the fixation element may be a planar spiral, a substantially helical spiral, or substantially spherical. In the substantially spherical form, the fixation element may have a diameter greater than the diameter of the lumen of the ureter. In another embodiment, the proximal portion of the elongated body portion is substantially more compressible than remaining portions of the elongated body portion. In this embodiment, the proximal portion of the elongated body portion will collapse with pressure exerted on it by adjacent body tissue, by peristaltic motion, or by sphincter contraction, for example.
In further embodiments, the retention module may have multiple tether connectors and/or multiple fixation elements to facilitate urinary drainage during conditions of peri-renal or peri-ureteral edema, for example. The tether connector of the retention module may be substantially elastic to provide a strain relief function and to minimize longitudinal movement of the stent in the ureter in the direction of the kidney when there is movement of the kidney relative to the bladder, such as during normal respiration. In different embodiments, the tether connector may be substantially rigid. In other embodiments, the elongated body portion may be substantially rigid to prevent deformation during the insertion of the device through the ureter. In another embodiment, the elongated body portion may define a plurality of openings along its length to further facilitate fluidic communication between the lumen of the body portion and the body tract where the body portion is disposed.
A second aspect of the invention describes a method of treating at least partial ureteral obstruction of a patient. The method according to the invention includes the steps of providing a medical device with an elongated body portion defining a lumen and having a proximal end, a distal end, a proximal portion, a distal portion, a retention module attached to the proximal end of the elongated body portion by a tether connector, and inserting the medical device into the patient such that the fixation element is positioned in the bladder of the patient.
The foregoing and other objects, features and advantages of the present invention disclosed herein, as well as the invention itself, will be more fully understood from the following description of preferred embodiments and claims, when read together with the accompanying drawings. In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
This invention generally concerns a drainage device that, when positioned within a body tract such as a duct, tube, or vessel of a mammal, assists in reducing fluid retention with minimal patient discomfort. For simplicity and for illustrative purposes, the invention is described here in the context of draining urine from the urinary tract such as a kidney, through a ureter, and into the urinary bladder. However, the invention is applicable to any situation that requires drainage of fluid from any site within the body. Application of the invention also applies to body sites in the body other than the urinary tract such as, for example, drainage from the gall bladder, or other biliary structures, to the duodenum.
Referring to
Typically, in a ureteral application, the length of the elongated body portion 10 ranges between about 18 cm to 30 cm, preferably about 18 cm to 20 cm. In one embodiment, the body portion 10 of the ureteral stent 5 includes at least one lumen, such as lumen 12 illustrated, for example, in
With continued reference to
In one embodiment according to the invention illustrated in
Referring to
The wall 17 in the distal region 40 of the elongated body portion 10, for example, as illustrated in
As shown in
The retention module 15, illustrated in
Referring to
According to one embodiment of the invention, the fixation element 30 of the retention module is manufactured from a polymer that permits fixation element 30 to remain buoyant. Some copolymers that may be used to manufacture fixation elements 30 include, for example, a copolymer such as PERCOFLUX® (Medi-Tech, Inc.), C-FLEX® (Xomed-Trease, Inc.), FLEXIMA™, or a high density polyethylene or PTFE such as TEFLON® (E.I. Du Pont De Nemours and Company, Inc.) that permit fixation element 30 to remain buoyant. In a particular embodiment according to the invention, the fixation element 30 is buoyant relative to the specific gravity of the medium, such as urine, in which the fixation element 30 is suspended. This characteristic permits at least the fixation element 30 of the retention module 15 to remain buoyant in the lumen 66 of the urinary bladder 60 illustrated in
Referring again to
Referring again to
Referring again to
The tether connector 25, according to the invention, extends from the proximal end 35 of the stent 5 and has a smaller diameter than the elongated body portion 10. Because of its small diameter, tether connector 25 minimizes ureteral reflux, (i.e., flow of urine back up the ureter toward the kidney during voiding) because the intramural tunnel 80 of the urinary bladder 60 is collapsed around the small diameter tether connector 25 when the urinary bladder contracts during voiding. Tether connector 25 also minimizes patient discomfort associated with obstructions in the ureteral orifice 70. The number, size and configuration of fixation elements 30, as described below, may be customized to accommodate the migration-prevention requirements of the particular stent to be implanted in the patient's body.
In another embodiment of the invention illustrated in
Referring again to
With the distal portion 40 of the stent 5 in place, the wire guide is withdrawn further from the lumen 12 of the elongated body portion 10 of the stent 5 followed by complete removal of the wire guide from the patient. The retention module 15 remains attached to the proximal drainage end 35 of the body portion 10 via the tether connector 25 at the attachment site 20. The tether connector 25 extends through the intramural tunnel 80 to the fixation element 30 and terminates in the lumen 66 of the urinary bladder 60. The stent 5 and the retention module 15 are selected according to the clinical needs of the patient and must be attached to the proximal portion 18 of stent 5 before the insertion of stent 5 into a body cavity.
Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is not to be limited to the preceding illustrative description but instead by the spirit and scope of the following claims.
Claims
1. A ureteral stent for placement in a ureter comprising:
- an elongated body portion defining a lumen, said body portion comprising a proximal end for placement within one of a ureter and a bladder of a patient, a distal end for placement within a kidney of the patient, a proximal portion, and a distal portion; and
- a retention module disposed proximal to said proximal end of said elongated body portion for retaining a portion of the stent in the bladder, said retention module comprising at least one bead having a diameter between 3 and 10 millimeters, the at least one bead being attached to the elongated body portion by at least one tether connector, wherein the at least one bead is substantially buoyant relative to urine.
2. The ureteral stent of claim 1, wherein the at least one bead has a size and configuration that prohibits the passage of the at least one bead from the bladder into a lumen of a ureter.
3. The ureteral stent of claim 1, wherein said proximal portion of said elongated body portion is substantially more compressible than the other portions of said elongated body portion.
4. The ureteral stent of claim 1, wherein the retention module includes a plurality of beads.
5. The ureteral stent of claim 1, wherein said at least one tether connector is substantially elastic.
6. The ureteral stent of claim 1, wherein said tether connector is substantially rigid.
7. The ureteral stent of claim 1, wherein said distal portion of said elongated body portion comprises a planar spiral loop for retention in the renal pelvis.
8. The ureteral stent of claim 1, wherein said elongated body portion is substantially rigid to prevent its deformation during insertion through the ureter.
9. The ureteral stent of claim 1, wherein said elongated body portion defines a plurality of openings along its length.
10. The ureteral stent of claim 1, wherein the at least one bead is substantially spherical.
11. The ureteral stent of claim 1, wherein said bead is substantially spherical, substantially oval, substantially tear-shaped, or substantially peanut-shaped.
12. The ureteral stent of claim 1, wherein said bead is made of a polymer.
13. A method of treating at least partial ureteral obstruction of a patient, comprising:
- (a) providing a medical device comprising an elongated body portion defining a lumen, the body portion comprising a proximal end for placement in one of a ureter and a bladder of the patient, a distal end for placement in a kidney of the patient, a proximal portion, and a distal portion, the medical device further comprising a retention module disposed proximal to said proximal end of the elongated body portion, said retention module comprising at least one bead attached to the elongated body portion by at least one tether connector, the bead having a diameter between 3 and 10 millimeters, the bead being substantially buoyant relative to urine; and
- (b) inserting the medical device into the patient such that the at least one bead is positioned in the bladder of the patient.
14. The method of claim 13, wherein the at least one bead has a size and configuration that prohibits the passage of the bead from the bladder into a lumen of a ureter.
15. The method of claim 13, wherein the retention module has a plurality of beads.
16. The method of claim 13, wherein said at least one tether connector is substantially elastic.
17. The method of claim 13 wherein said tether connector is substantially rigid.
18. The method of claim 13 wherein said distal portion comprises a planar spiral loop for retention in the renal pelvis.
19. The method of claim 13, wherein said elongated body portion is substantially rigid to prevent its deformation during insertion through the ureter.
20. The method of claim 13, wherein said elongated body portion defines a plurality of openings along its length.
21. The method of claim 13, wherein the bead is substantially spherical.
22. The method of claim 21, wherein the diameter of the bead is greater than the diameter of a lumen of a ureter.
23. The method of claim 13, wherein said bead is substantially spherical, substantially oval, substantially tear-shaped, or substantially peanut-shaped.
24. The method of claim 13, wherein said bead is made of a polymer.
25. A medical device for use within a body cavity, the medical device comprising:
- an elongated body portion defining a lumen, said elongated body portion comprising a proximal end for placement within one of a ureter and a bladder of a patient, a distal end for placement within a kidney of the patient, a proximal portion and a distal portion and said elongated body portion including a plurality of pores, said distal portion comprising a planar spiral; and
- a plurality of retention modules, at least one of said plurality of retention modules being attached to said proximal end of said elongated body portion, said at least one of said plurality of retention modules comprising at least one substantially spherical bead attached to the proximal end of said elongated body portion by a substantially elastic tether connector, said bead having a diameter between 3 and 10 millimeters and being substantially buoyant relative to urine.
26. A ureteral stent for placement in a ureter comprising:
- an elongated body portion defining a lumen, the body portion comprising a proximal end, a distal end, a proximal portion, and a distal portion, the proximal portion of the elongated body portion is substantially more compressible than the other portions of the elongated body portion; and
- a retention module disposed proximal to the proximal end of the elongated body portion, the retention module having a first fixation element attached to the elongated body portion by a tether connector, the retention module having a second fixation element attached to the elongated body portion.
27. The ureteral stent of claim 26, wherein the retention module has a size and configuration that prohibits the passage of the fixation element from a bladder of a patient into a lumen of a ureter of the patient.
28. A ureteral stent for placement in a ureter comprising:
- an elongated body portion defining a lumen, the body portion comprising a proximal end, a distal end, a proximal portion, and a distal portion, the proximal portion of the elongated body portion is substantially more compressible than the other portions of the elongated body portion; and
- a retention module disposed proximal to the proximal end of the elongated body portion, the retention module having a first fixation element and a second fixation element attached to the elongated body portion by a tether connector.
29. The ureteral stent of claim 26, wherein the first fixation element includes a substantially spiral configuration.
30. A ureteral stent for placement in a ureter comprising:
- an elongated body portion defining a lumen, the body portion having a proximal end and a distal end; and
- a retention module disposed proximal to the proximal end of the elongated body portion, the retention module having a first fixation element attached to the elongated body portion by a tether connector, the first fixation element having a substantially spiral configuration, the retention module having a second fixation element attached to the elongated body portion.
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Type: Grant
Filed: Dec 11, 2001
Date of Patent: May 9, 2006
Patent Publication Number: 20030109930
Assignee: Boston Scientific Scimed, Inc. (Maple Grove, MN)
Inventors: Scott Bluni (Sudbury, MA), Barry Gellman (North Easton, MA)
Primary Examiner: Thomas Barrett
Application Number: 10/014,678
International Classification: A61F 2/36 (20060101);